According to the well known principles of fluid dynamics, as an aircraft flies through the air, a boundary layer of turbulent air develops about all exterior surfaces of the aircraft. In order to properly deploy an ordnance from underneath the aircraft, the ordnance must be pushed through this boundary layer before being fully released from control. If the ordnance is not pushed through the boundary layer, the turbulent air within the boundary layer may act unpredictably upon the ordnance, perhaps causing it to bounce against the under surface of the aircraft thereby causing damage.
Typically, ordnance ejector systems function either by mechanical linkages which push the ordnance through the turbulent boundary layer, or axially moving reciprocating shafts which push the ordnance through the turbulent boundary layer. Examples of the linkage type ordnance ejector systems include U.S. Pat. Nos. 4,440,365 to Holtrop, issued Apr. 3, 1984, 4,679,751 to Peterson, issued July 14, 1987 and 4,600,171 to Kalisz, issued July 15, 1986. An example of the axially moving reciprocating shaft type ordnance ejector system is the Sosnowski et al, U.S. Pat. No. 4,572,053, issued Feb. 25, 1986.
Typically, the linkage type ordnance ejector systems include a forward and rearward linkage connected to a rail member, wherein the rail member releasably retains the ordnance thereto. It has been found particularly advantageous to individually control the forward and rearward linkage with separate, dedicated actuators. Such actuators typically comprise pyrotechnically operated pistons. Individual control of the forward and rearward linkages allows the ordnance ejector system to be more easily adapted to different ordnance types. That is, different types of ordnance may require different ejection velocities, different attitudes at release, etc. Unless independent control of the forward and rearward linkages is provided, such adaptations can not be made except by physical changes to the individual links.
One significant concern which becomes particularly acute when the forward and rearward linkages are controlled by independent actuators is that the forward end, or nose, of the ordnance must be in a downward attitude as the ordnance is ejected. This nose down condition of the ordnance is essential to prevent the ordnance from being thrust back upwardly into the bottom of the aircraft. Therefore, when the ordnance is ejected in a nose down condition, it will be pushed away from the aircraft to ensure a safe ejection.
As mentioned above, however, individual control of the forward and rearward linkages by independent actuators raises concern that the ordnance may accidently be released in a nose end up condition. This would occur if the actuator controlling the rearward linkage were to fire chronologically before the actuator controlling the forward linkage. Although the prior art undoubtedly provided safe guards to ensure the sequential firing of the actuators controlling the forward and rearward linkages, such safe guards have not been foolproof.